Long term evolution (LTE) based on 3rd generation partnership project (3GPP) technical specification (TS) release 8 is a promising next-generation mobile communication standard.
As disclosed in 3GPP TS 36.211 V8.5.0 (2008-12) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)”, a physical channel of the LTE can be classified into a data channel, i.e., a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH), and a control channel, i.e., a physical downlink control channel (PDCCH), a physical control format indicator channel (PCFICH), a physical hybrid-ARQ indicator channel (PHICH), and a physical uplink control channel (PUCCH).
A PDCCH (i.e., a downlink control channel) carries a downlink grant for receiving the PDSCH of a UE (UE) and an uplink grant for transmitting the PUSCH of a UE. A PUCCH (i.e., an uplink control channel) carries an uplink control signal (e.g., ACK (positive-acknowledgement)/NACK (negative-acknowledgement) signals for a HARQ), a CQI (Channel Quality Indicator) indicating the condition of a downlink channel, an SR (Scheduling Request) for requesting the allocation of radio resources for uplink transmission, and so on.
To guarantee a higher data rate, a technique using a multi-antenna has been introduced.
An HARQ based on the physical channels of the existing 3GPP LTE is performed by taking transmission using a single antenna into consideration. However, if HARQ based on single antenna transmission is applied to a multi-antenna without change, the execution of an HARQ may not be efficient.
Accordingly, there is a need for a method and apparatus capable of performing an HARQ in a multi-antenna system.